Physics 132, Practice Final Exam Multiple Choice Questions. Circle the letter that corresponds to your choice for the correct answer to each problem.

Transcription

1 Cicle the lette that coespons to you choice fo the coect answe to each poblem. 1. A squae loop of wie lies in the plane of the page. A eceasing magnetic fiel is iecte into the page. The inuce cuent in the loop is: A) counteclockwise. B) clockwise. C) zeo. D) epens upon whethe o not B is eceasing at a constant ate. ) clockwise in two of the loop sies an counteclockwise in the othe two. 2. A point chage, -3q, lies at the cente of a conucting, cubical shell with sies of length 2. The shell has a net chage of -3q. The net chage on the oute suface of the shell is: A) 6q B) 3q C) zeo D) -3q ) -6q 3. A paticle (mass m, chage -q) with spee v entes the egion between two paallel plates though a vey small hole, as shown. The potential iffeence between the two plates is V an thei sepaation is. The change in kinetic enegy of the paticle afte it taveses this egion is best given by: A) -qv/ B) 2qV/mv 2 C) qv D) ½ mv 2 ) none of these m, -q v 0 +V 4. Chage is istibute unifomly on the suface of a lage flat plate. The electic fiel 2 cm fom the plate is 30 N/C. The electic fiel 4 cm fom the plate is: A) 120 N/C B) 80 N/C C) 30 N/C D) 15 N/C ) 7.5 N/C 5. Two small chage objects epel each othe with a foce F when sepaate by a istance. If the chage on each object is euce to one-fouth of its oiginal value an the istance between is euce to /2, the foce becomes: A) F/16 B) F/8 C) F/4 D) F/2 ) F Page 1

2 6. The figue shows the motion of electons in a wie which is nea the Noth pole of a magnet. The wie will be pushe: A) towa the magnet B) away fom the magnet C) ownwas D) upwas ) along its length N electon flow 7. Two wies mae of iffeent mateials have the same unifom cuent ensity. They cay the same cuent only if: A) thei lengths ae the same. B) thei coss-sectional aeas ae the same. C) both thei lengths an coss-sectional aeas ae the same. D) the potential iffeences acoss them ae the same. ) the electic fiels in them ae the same. 8. In the fomula F = qvxb: A) F must be pepenicula to v but not necessaily to B. B) F must be pepenicula to B but not necessaily to v. C) v must be pepenicula to B but not necessaily to F. D) all thee vectos must be mutually pepenicula. ) none of the above. 9. Two point chages, 8x10-9 C an -2x10-9 C ae sepaate by 4 m. The electic fiel magnitue (in units of V/m) miway between them is: A) 9x10 9 B) 13,500 C) 135,000 D) 36x10-9 ) Two point chages, q 1 an q 2, ae place a istance apat. The electic fiel is zeo at a point P between the chages on the line segment connecting them. We conclue that: A) q 1 an q 2 must have the same magnitue an sign B) P must be miway between q 1 an q 2 C) q 1 an q 2 must have the same sign but may have iffeent magnitues D) q 1 an q 2 must have equal magnitues an opposite signs ) q 1 an q 2 must have opposite signs an may have iffeent magnitues 11. esistances of 2.0 Ω, 4.0 Ω, an 6.0 Ω, an a 24 V battey ae all in seies. The cuent in the 2.0 Ω esisto is: A) 12 A B) 4.0 A C) 2.4 A D) 2.0 A ) 0.50 A Page 2

3 12. A cuent of 0.3 A is passe though a lamp fo 2 minutes using a 6 V supply. The enegy issipate by the lamp uing the 2 minutes is: A) 1.8 J B) 12 J C) 20 J D) 36 J ) 216 J 13. Let Q enote chage, V enote potential iffeence, an U enote stoe enegy. Of these quantities, capacitos in seies must have the same: A) Q only D) Q an U only B) V only ) V an U only C) U only 14. Choose the coect statement: A) A poton tens to go fom a egion of low potential to a egion of high potential B) The potential of a negatively chage conucto must be negative C) If =0 at a point P, then V must be zeo at P D) If V=0 at a point P, then must be zeo at P ) None of the above ae coect 15. If 500 J of wok ae equie to cay a 40 C chage fom one point to anothe, the potential iffeence between these two points is: A) 12.5 V D) epens on the path B) 20,000 V ) none of these C) 0.08 V 16. Two unchage metal sphees, L an M, ae in contact. A negatively chage o is bought close to L, but not touching it, as shown. The two sphees ae slightly sepaate an the o is then withawn. As a esult: A) both sphees ae neutal. B) both sphees ae positive. C) both sphees ae negative. D) L is negative an M is positive. ) L is positive an M is negative L M insulating stans 17. ach plate of a capacito stoes a chage of magnitue 1x10-3 C when a 100 V potential iffeence is applie. The capacitance is: A) 5 µf D) 100 µf B) 10 µf ) none of these C) 50 µf Page 3

4 18. Two wies mae of the same mateial have the same length but iffeent iametes. They ae connecte in paallel to a battey. The quantity that is NOT the same fo the wies is: A) the en-to-en potential iffeence B) the cuent C) the cuent ensity D) the electic fiel ) the electon ift velocity 19. A soli insulating sphee of aius contains a unifom volume istibution of positive chage. Which of the gaphs below coectly gives the magnitue of the electic fiel as a function of? I II III IV V A) I. B) II. C) III. D) IV. ) V. 20. Chages Q, -Q, an q ae place at the vetices of an equilateal tiangle as shown. The total foce exete on the chage q is: A) towa chage Q. B) towa chage -Q. C) away fom chage Q. D) left. ) ight. + q -Q - + Q Page 4

5 21. Thee esistos, 1, 2, 3, ae in seies with each othe. 1 < 2 < 3. The cuent though 1 is i. Which statement is tue? A) 1 has the lagest potential iffeence acoss it. B) 3 has the lagest potential iffeence acoss it. C) The potential iffeence acoss each esisto is the same. D) The powe issipate by each esisto is the same. ) If the esistos ae mae of the same mateial, an have the same coss-sectional aea, then 1 is the longest. 22. A cuent i goes though a wie that extens fom infinitely fa up, follows a 90 o ben, an continues infinitely fa to the ight as shown. What is the magnitue of the magnetic fiel at P, a istance below? A) 2µ i o π D) µ i o 4π B) µ i o π ) zeo C) µ o i 2π P i 23. A cetain physics textbook shows a egion of space in which two electic fiel lines coss each othe. We shoul conclue that: A) at least two point chages ae pesent. B) an electical conucto is pesent. C) an insulato is pesent. D) the fiel points in two iections at the same place. ) the autho of the textbook mae a mistake. 24. The capacitance of a paallel-plate capacito can be incease by: A) inceasing the chage. D) eceasing the plate sepaation. B) eceasing the chage. ) eceasing the plate aea. C) inceasing the plate sepaation. 25. Chage Q is istibute unifomly thoughout a spheical insulating shell. The net electical flux in Nm 2 /C though the oute suface of the shell is: A) zeo B) Q/ε o C) 2Q/ε o D) Q/4ε o ) Q/2πε o Page 5

6 26. A 2 ohm esisto an 4 ohm esisto ae connecte in paallel to a 6 volt battey. The powe issipate by the 2 ohm esisto is: A) 8 W D) 18 W B) 6 W ) None of these C) 9 W 27. A kiloampee - hou is a unit of: A) cuent D) chage B) chage pe time ) enegy C) powe 28. Points an T ae each a istance fom each of two equal an opposite chages as shown. If k = 1/4πε o, the wok equie to move a negative chage q fom to T is: Q + - -Q T A) zeo D) kqq/(4 2 ) B) kqq/ 2 ) kqq/(2) C) kqq/ 29. The cuent is zeo in a conucto when no potential iffeence is applie because: A) the electons ae not moving. B) the electons ae not moving fast enough. C) fo evey electon with a given velocity, v, thee is anothe with velocity, -v. D) equal numbes of electons an potons ae moving togethe. ) othewise Ohm s law woul not be vali. Page 6